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The present invention pertains generally systems and methods for displaying representations of weather phenomenon over maps of geographic locations for televised weather presentations, and the like, and computer based systems and methods for preparing and manipulating such displays including systems and methods for tracking and displaying the expected future path of such weather phenomena.
Various systems and methods are used for providing viewers of broadcast and cable television weather presentations with informative and accurate weather information. Typically, such systems provide a display of weather phenomena, e.g. clouds, rain, storms, etc., overlaid on a map of a geographical area of interest. Such displays were originally created by drawing representations of weather phenomena, or placing pre-made weather symbols, on a physical map of an area of interest. The image of the map was then broadcast to viewers, usually with a weather presenter positioned in front of the map to provide an explanation of the map display. Computer systems are now employed to facilitate the generation of weather displays, using computer generated graphics with animation.
A typical computer-implemented system for preparing a weather presentation will include detailed digital maps of geographic areas of interest stored for access by the computer. Weather information, such as satellite imagery and/or weather radar information, such as NEXRAD weather radar information provided by the government and live local weather radar data, is provided to the system. The system processes the weather information to generate a display, e.g., of the current position of weather phenomena, such as a storm cell, and, e.g., of the projected path of the weather phenomena over a future period of time. A graphical display and/or representation of the current position, and projected future path, of the weather phenomena is then overlaid on the digital maps to create a digital display of current and predicted weather for a particular area of interest. Other information provided on the weather display may include a display of the characteristics of the weather phenomena displayed, e.g., whether a storm cell contains elements of hail or tornadoes, as well as a graphical and/or textual display of when a particular weather condition is expected to reach a particular location.
The ability to combine weather information from various weather information sources with geographical data to determine, e.g., the current position of weather phenomena and predicted path of such phenomena with respect to geographic locations of interest, and then to generate a combined weather/geographical display in an accurate and informative manner, can provide a challenge in that weather information sources, geographical databases, and screen displays employ various different coordinate systems to identify the positions of weather phenomena, geographical locations, and display positions within their respective areas. For example, weather radar systems may provide information on the current position of weather phenomena, e.g., a storm being tracked by the weather radar, as an angular direction of the storm from the radar source (azimuth) and distance of the storm from the radar source (range). An example of such a weather radar system is the NEXRAD radar service, which provides such storm attribute position information in degrees and nautical miles, along with detailed information on the contents of the storm, as well as a forecast movement angle (storm path) in degrees and forecast movement speed in nautical miles per hour. Conventional commercially available geographic databases typically provide location information for places included in the database in conventional latitude/longitude (lat/lon) coordinates. In order to combine the NEXRAD weather radar information with the geographical database information, e.g., to determine which places identified in the geographical database are currently affected by, or are in the predicted path of, a storm identified in the NEXRAD information, the storm location information provided by NEXRAD in range and azimuth and the geographical information provided in the geographical database in lat/lon must be converted to a common coordinate system. In conventional computer-implemented systems for preparing weather presentations, this is achieved by converting the location of a storm or other weather phenomena identified by range and azimuth in the NEXRAD, or other radar, data to lat/lon coordinates, in a conventional manner, such that the position of the storm or other weather phenomena, and predicted path of movement thereof, may be compared easily to places identified by lat/lon coordinates in the geographical database, to determine which places are currently, or in the future are likely to be, affected by the storm or other weather phenomena. The storm location/predicted path of movement in lat/lon may then be combined with the geographical/map database in lat/lon coordinates to generate a graphical display of the weather phenomena overlaid on a graphical map display by converting the lat/lon coordinates of the weather phenomena and geographic data into two-dimensional screen coordinates in a conventional manner.
Although conceptually straightforward, the conventional method of converting weather radar information provided in azimuth and range from a known radar site location to lat/lon coordinates is considerably limited and inflexible. The conversion to two-dimensional lat/lon coordinates does not take into account any altitude information, i.e., neither altitude above/below sea level nor altitude above the Earth""s surface, of weather phenomena information which may be provided by or extracted from a weather radar or other weather information source. Thus, valuable information may be lost in the conversion of weather information to lat/lon coordinates which do not take into account weather phenomena altitude or variations in altitude of the Earth""s topology. Furthermore, although it may be convenient to convert the range and azimuth of a storm location from a given fixed NEXRAD or other radar location, for which the lat/lon coordinates are known, to lat/lon coordinates, such a conversion may not be as convenient for weather phenomena information provided from current or future weather information sources which do not provide weather information in such a manner, e.g., satellite based weather observation systems. Thus, such a conversion to lat/lon coordinates may not be effective or useful when it is desired to combine weather information from a variety of different weather information sources to generate a weather presentation and display.
What is desired, therefore, is a system and method for processing weather information in which weather information from one or more weather information sources is converted into a universal three-dimensional coordinate system. Preferably, the current location of weather phenomena may be converted into the universal three-dimensional coordinate system from weather information provided by one or more weather information sources, and a predicted path of movement of such weather phenomena may be generated in the three-dimensional coordinate system. Preferably, locations of selected places of interest may be provided in, or converted to, the three-dimensional coordinate system for comparison with the weather phenomena position and predicted path of movement information in the three-dimensional coordinate system, to determine if the selected places of interest are currently affected by, or are in the predicted path of, the weather phenomena. The position of weather phenomena, and predicted path thereof, in the three-dimensional coordinate system may preferably be converted to two-dimensional screen display coordinates for display, e.g., as a graphical representation of the current position and predicted path of weather phenomena overlaid on a geographical map display, showing areas currently affected by, or predicted to be affected by, the weather phenomena.
The present invention provides a system and method for processing weather information in which weather information from one or more weather information sources is converted into a universal three-dimensional XYZ space coordinate system centered at the center of the Earth. The current location of detected weather phenomena, based on weather information provided from the one or more weather information sources, may be converted into the three-dimensional XYZ coordinate system, and a predicted future path of the weather phenomena derived therefrom in the XYZ coordinate system. Geographical database information, including the locations of places of interest which are either provided in, or converted to, the universal three-dimensional XYZ coordinate system, may be combined with the current location and predicted path of movement of the weather phenomena in the XYZ coordinate system to determine which places of interest are currently, or are likely to be, effected by the weather phenomena. The location and predicted path of weather phenomena in the XYZ coordinate system may be converted to a two-dimensional xy screen coordinate system for display on a display screen in combination with a geographical map display of a graphical representation of the current position and path of the weather phenomena overlaid on the geographical map display. Such a combined weather/geographical map display may include an indication of places of interest which are currently affected by the displayed weather phenomena, or are in the predicted path of the weather phenomena.
A system for processing weather information in accordance with the present invention may be implemented in software on a conventional commercially available computer processor or system. The system may receive weather information from various sources, such as NEXRAD or other weather radar information, and other weather information from other weather information sources. Weather information received by the system is converted by the system to the universal three-dimensional XYZ coordinate system using coordinate conversion routines stored in memory associated with the system. The system preferably determines the current location and a predicted path of the weather phenomena in the three-dimensional XYZ coordinate system. The system may preferably combine the weather phenomena location, and predicted path thereof, in the XYZ coordinate system, with geographic location information to determine locations of interest which are currently, or in the future are likely to be, affected by the weather phenomena. The system may also produce a graphical weather display, including a graphical representation of the weather phenomena overlaid on a map of a geographical area of interest, showing, e.g., the current location of the weather phenomena and an indication of the future path of the weather phenomena, along with an indication of selected places of interest in the geographical area displayed which are in the predicted path of the weather phenomena. Such a weather display may, for example, be saved or broadcast live as part of a live television weather presentation.
Weather information provided to a system for processing weather information in accordance with the present invention may be provided from a NEXRAD weather radar system. NEXRAD provides storm attribute information which includes the current location of a storm identified by the direction of the storm in degrees from the radar source (azimuth) and the distance of the storm in nautical miles from the radar source (range). The geographic location of the radar source in latitude and longitude (lat/lon) is known. In accordance with the present invention, the storm location in azimuth and range from the radar site is converted into three-dimensional coordinates in an XYZ space defined on the center of the Earth. For example, the XYZ coordinate 0,0,0 may be defined at the center of the Earth, with the y-axis defined by the line extending from the center of the Earth to the North Pole, the x-axis defined by the line extending from the center of the Earth to the Equator at longitude 0, and the z-axis defined by the line extending from the center of the Earth to the Equator at longitude xe2x88x9290 (90 degrees West).
In accordance with the present invention, the location of a storm in the three-dimensional XYZ coordinate system may be derived from the location of the storm as provided in the NEXRAD storm attribute information by a two xe2x80x9crotationxe2x80x9d process in which the XYZ coordinate of the known location of the NEXRAD radar site is shifted first by the distance of the storm from the radar site (range) as provided in the NEXRAD storm attributes, and then by the direction (azimuth) of the storm from the radar site as provided in the NEXRAD storm attributes, to generate a new point in XYZ space which corresponds to the location of the storm as provided by the NEXRAD storm attributes. This conversion procedure may begin, for example, by first determining the position of the fixed NEXRAD radar site in the universal three-dimensional XYZ coordinate system. This is accomplished by a straightforward conversion of the known location of the NEXRAD site in lat/lon into an XYZ coordinate in the three-dimensional XYZ coordinate system. The original XYZ position of the radar site is shifted in the three-dimensional XYZ space by xe2x80x9crotatingxe2x80x9d the original position by an amount corresponding to the distance from the radar site to the storm location as provided in the NEXRAD storm attributes, along a rotation axis defined by a cross product of the vector extending from the center of the Earth to the north pole and a vector extending from the center of the Earth to the radar site XYZ location in the three-dimensional XYZ space. The resulting first rotation shifts the original XYZ location due north by an amount corresponding to the distance (range) value provided in the NEXRAD storm attributes, generating a position due north of the radar site location. In the second xe2x80x9crotation,xe2x80x9d the position obtained in the first rotation is rotated around the vector extending from the center of the Earth to the original XYZ position of the NEXRAD radar site by the azimuth angle provided in the NEXRAD storm attributes. This second rotation results in the XYZ coordinates of the storm location in a universal three-dimensional XYZ coordinate system in accordance with the present invention.
Once the location of a storm being detected and tracked by NEXRAD is converted into the three-dimensional XYZ coordinate system, a predicted future path of movement of the storm may be derived in the three-dimensional XYZ coordinate system, e.g., using the forecasted movement direction and speed information provided in the NEXRAD storm attributes, or in another manner. The NEXRAD location and predicted path may then be compared in the three-dimensional XYZ coordinate space with selected geographic locations, e.g., provided in a geographic location database, to determine which selected locations are in the path of the storm. If the selected locations are provided in lat/lon coordinates in a conventional geographic database, the comparison between the selected locations and the NEXRAD storm location and path in the three-dimensional XYZ coordinate system may require first converting the selected locations from lat/lon coordinates to XYZ coordinates. Other processing of the NEXRAD or other weather information in the XYZ coordinate system may also be performed.
A graphical weather display of a weather phenomena location, path, and affected locations, derived, in accordance with the present invention, in three-dimensional XYZ coordinate space, may be displayed, e.g., as graphical representations of the weather location and predicted path overlaid on a geographic map of an area of interest. To generate such a display, the weather location and path in the three-dimensional XYZ coordinate system must be converted into two-dimensional xy screen coordinates for display. This may be accomplished without converting the weather location or path information to intermediate lat/lon coordinates by employing a search routine to determine the two-dimensional screen xy coordinates which correspond to the three-dimensional XYZ coordinates of a storm, storm path, or other weather phenomena. For example, to determine the screen y-coordinate, the screen y-coordinates for latitude 90 and xe2x88x9290 are calculated. A screen y-coordinate to be tested is then selected. The location of the selected screen y-coordinate in three-dimensional XYZ space is then computed. The Y component of the point to be plotted and the Y component of the screen y-coordinate being tested are then compared. The selected screen y-coordinate is then adjusted by the results of the comparison. This procedure is repeated until the Y-coordinates of the three-dimensional XYZ points to be plotted and the screen y-coordinate tested are equal. A similar binary search routine may be performed to determine the screen x-coordinate of a point in three-dimensional XYZ space to be displayed on the screen display.
Further objects, features, and advantages of the invention will be apparent from the following detailed description, taken in conjunction with accompanying drawings.